Proposed research concerns the hormonal regulation of avian vitellogenin and very low density lipoprotein synthesis. Multiple species of vitellogenin will be related to the family of yolk proteins derived from the vitellogenins via peptide mapping and immunological analyses. The non-phosphorylated vitellogenin precursors will be characterized and related to specific plasma vitellogenins. The post-translational processing of the non-phosphorylated vitellogenin precursors will be studied in avian hepatocytes. Clones of cDNA representing the individual vitellogenin messenger RNA's will be isolated and used to study the differential expression of the multiple vitellogenin genes. The relationship between apolipoprotein B and apolipoprotein II of very low density lipoprotein will be examined in terms of their regulatory characteristics and in terms of the physical association of these apolipoproteins in the VLDL particle.